1. Field of the Invention
The present invention relates to a double-balanced mixer comprising a diode ring which is connected with respective balancing circuit portions for a local oscillator signal and for a high frequency signal and with a capacitively-loaded conductor branch for an intermediate frequency signal.
2. Prior Art
A double-balanced mixer of this type is disclosed in the article by W. Brinlee, K. Varian and M. Pavio, entitled "A Novel Planar Double-Balanced 6-8 GHz MMIC Mixer", IEEE MTT Symposium Digest, 1994, Session TV1A-2. The diode ring of this double-balanced mixer comprises four diodes connected side-by-side whose connecting lines form an asymmetric figure 8. The respective balancing circuit portions for the RF signal and for the local oscillator signal comprise two conductor lines coupled with each other, between which concentrated capacitances are provided from amplification of the coupling. Its design is made difficult because of the use of concentrated capacitances, especially when exact electrical properties are desired at very high frequencies (30 GHz). The conductor branch for the intermediate frequency signal is purely capacitatively loaded, whereby troublesome resonances can arise in certain cases.